InChI=1S/C21H22O7/c1-10(2)4-5-11-13(22)8-16(25)20-17(26)9-18(28-21(11)20)12-6-19(27-3)15(24)7-14(12)23/h4,6-8,18,22-25H,5,9H2,1-3H3